LAS VEGAS, Nevada (CNN) -- A fire at the Monte Carlo Resort and Casino in Las Vegas last week was likely caused by flying molten metal from a cutting torch being used by construction crews, the Clark County Fire Department said Thursday.

The Friday fire charred the top of two of the casino's three wings.

It caused no major injuries but triggered the evacuation of visitors and employees.

At the time the blaze began, workers on the roof of the building were cutting corrugated steel products used for a walkway being installed around the interior border of the roof, the fire department said in a statement.

"It appears that no slag mats were used to catch the molten metal and no fire watch had been posted. Additionally, the contractor responsible for the work did not obtain the necessary 'hot works' permit. We are now reviewing whether to cite the contractor."

The department said such citations are misdemeanors and are punishable by a fine of up to $1,000 and/or six months in jail.

Don't Miss

Vegas resort casino fire fully contained

The county requires contractors to obtain a hot works permit from the fire department when using a torch, the statement said.

The contractor -- Union Erectors Limited Liability Company -- had a permit from the county's Department of Development Services to install window-washing equipment at the hotel, but no hot works permit, the fire department said.E-mail to a friend